Magnetic random-access memory (MRAM) is a non-volatile memory for long-term data storage. A typical MRAM device includes an array of memory cells. Word lines extend along rows of the memory cells, and bit lines extend along columns of the memory cells. Each memory cell is thus located at a cross point of a word line and a bit line. The memory cell stores a bit of information as an orientation of a magnetization. The magnetization of each memory cell may have one of two stable orientations at any given time, parallel and anti-parallel, which correspond to logical values of zero and one.
To read the value stored at a desired memory cell, the appropriate word and bit lines are biased relative to one another, and the current through the cell is determined. Because the resistance of the memory cell is dependent on its magnetic orientation, the current measured is likewise dependent on the magnetic orientation of the memory cell.